Gentian is an herb. The root of the plant and, less commonly, the bark are used to make medicine.Gentian is used for digestion problems such as loss of appetite, fullness, intestinal gas, diarrhea, gastritis, heartburn, and vomiting. It is also used for fever, hysteria, and high blood pressure. Some people use gentian to prevent muscle spasms, treat parasitic worms, start menstrual periods, and as a germ killer.Gentian is applied to the skin for treating wounds and cancer.